A power tool includes a tool accessory, a motor, a control module, a power supply, and an operating switch. The operating switch includes a trigger mechanism, a current switch coupled to the trigger mechanism to be actuated by the trigger mechanism for connecting and disconnecting the electrical connection between the power supply module and the motor, and a signal switch coupled to the trigger mechanism to be actuated by the trigger mechanism at least configured to output a control signal to the control module to control the start of the motor.

Method and system for protecting induction motors from stalled start conditions provide a motor overload protection device that includes a stalled start detector capable of differentiating long start from stalled start conditions. This helps the motor overload protection device identify a stalled start condition right away and trip immediately rather than allowing the motor to continue drawing locked rotor current for the duration of the startup interval. Such a motor overload protection device may be used with any suitable multiphase induction motors, including two-phase motors, three phase motors, and the like. And because only the motor phase currents are used to detect the stalled start condition, the motor overload protection device disclosed herein does not require voltage phase shift information and/or motor speed measurements, thereby simplifying overall management of the motor.

Method and system for protecting induction motors from stalled start conditions provide a motor overload protection device that includes a stalled start detector capable of differentiating long start from stalled start conditions. This helps the motor overload protection device identify a stalled start condition right away and trip immediately rather than allowing the motor to continue drawing locked rotor current for the duration of the startup interval. Such a motor overload protection device may be used with any suitable multiphase induction motors, including two-phase motors, three phase motors, and the like. And because only the motor phase currents are used to detect the stalled start condition, the motor overload protection device disclosed herein does not require voltage phase shift information and/or motor speed measurements, thereby simplifying overall management of the motor.

The invention relates to a method for jointly controlling asynchronous machines (2; 3) of a motor vehicle (1) having a first asynchronous machine (2) and a second asynchronous machine (3) for driving the motor vehicle (1); an inverter (4), which is designed to supply the first asynchronous machine (2) and the second asynchronous machine (3) with a common stator voltage (5) at a common stator frequency (6). The method comprises the steps of determining a specified setpoint drive torque (11) of the motor vehicle (1) for a current driving situation of the motor vehicle (1); sensing a first rotational speed (7a) of the first asynchronous machine (2) and a second rotational speed (7b) of the second asynchronous machine (3); determining a common operating strategy of the first asynchronous machine (2) and of the second asynchronous machine (3) according to the specified setpoint torque (11) while taking into account the sensed rotational speeds (7a; 7b); and controlling the stator voltage (5) and the stator frequency (6) in order to set the drive torques (9a; 9b) of the asynchronous machines (2; 3) according to the operating strategy.

A generator starter of a turbomachine, including an asynchronous electric machine configured so as to operate in motor mode during a starting phase of the turbomachine while being supplied by an electrical source, and so as to operate in generator mode after the starting phase of the turbomachine in order to supply an electrical load. An inverter is arranged between the electrical source and the asynchronous machine with at least two alternating current terminals coupled to the asynchronous machine, and a control unit for the inverter configured to supply the asynchronous machine with a starting current in motor mode and a magnetisation current in generator mode. The asynchronous machine includes at least one first stator winding connected to the alternating current terminals to be supplied with the starting current in motor mode and with the magnetisation current in generator mode, and at least one second stator winding connected to the electrical load in generator mode.

A generator starter of a turbomachine, including an asynchronous electric machine configured so as to operate in motor mode during a starting phase of the turbomachine while being supplied by an electrical source, and so as to operate in generator mode after the starting phase of the turbomachine in order to supply an electrical load. An inverter is arranged between the electrical source and the asynchronous machine with at least two alternating current terminals coupled to the asynchronous machine, and a control unit for the inverter configured to supply the asynchronous machine with a starting current in motor mode and a magnetisation current in generator mode. The asynchronous machine includes at least one first stator winding connected to the alternating current terminals to be supplied with the starting current in motor mode and with the magnetisation current in generator mode, and at least one second stator winding connected to the electrical load in generator mode.

In a drive control apparatus for a multiple-winding motor including a power converter for driving a winding group per each winding group of a multiple-winding motor having a plurality sets of winding groups, a compensation amount calculator obtains, by using a signal of a first controller controlling a first power converter driving a first winding group among the winding groups, a compensation amount for compensating a signal of an other controller controlling an other power converter other than the first power converter, based on the compensation amount obtained by the compensation amount calculator. A signal of the other controller is compensated to control the other power converter, and the first power converter is controlled without compensating a signal of a first controller.

One embodiment describes a method that includes determining, using a control circuitry, temperature of a switching device before a make operation by applying a measurement current to an operating coil of the switching device, wherein the measurement current is insufficient to make the switching device; and determining voltage at the operating coil when the measurement current is applied, in which the voltage at the operating coil is directly related to the temperature. The method further includes determining, using the control circuitry, when to apply a pull-in current to the operating coil to close the switching device based at least in part on the voltage at the operating coil, such that the switching device makes at a desired time.

One embodiment describes a method that includes determining, using a control circuitry, temperature of a switching device before a make operation by applying a measurement current to an operating coil of the switching device, wherein the measurement current is insufficient to make the switching device; and determining voltage at the operating coil when the measurement current is applied, in which the voltage at the operating coil is directly related to the temperature. The method further includes determining, using the control circuitry, when to apply a pull-in current to the operating coil to close the switching device based at least in part on the voltage at the operating coil, such that the switching device makes at a desired time.

A method for starting and stopping an asynchronous motor by way of a soft starter. The method includes the following steps: determining ignition options of one or more thyristors of the soft starter that are possible at a future calculation time; predicting the motor behavior for the determined ignition options, if an ignition of one or more thyristors of the soft starter is carried out; based on the predicted motor behavior, deciding whether an ignition option is to be selected and which is to be selected; and generating one or more ignition signals for one or more thyristors, if the decision for an ignition option has been made.